Physics - Center of Mass Question with Solution | TestHub

For calculating centre of mass of combination of bodies we can assume whole mass of each of the bodies to be concentrated at their centre of mass.

For calculating torque of gravitational force on a body we can assume whole mass to be concentrated at centre of mass in uniform gravitational field.

For calculating moment of inertia of a body about some axis we can assume whole mass to be concentrated at centre of mass.

For a system, we can write the momentum as $M{\vec{V}}_{com}$, where $M$ is the mass of the system and ${\vec{V}}_{com}$ is the velocity of the system. Even though the velocities of bodies within the system can differ from the velocity of the center of mass of the system, the total momentum is given by this expression.